BACKGROUND: The wide diffusion of multicomponent collection in donor apheresis has led to the yielding of different components, such as plasma‐reduced platelet‐pheresis at high PLT concentration. We investigated whether this collection modality could induce more PLT activation compared to standard plateletpheresis. STUDY DESIGN AND METHODS: Forty‐one plateletpheresis collections (20 Trima and 21 Spectra LRS Turbo v.7.0, COBE) were evaluated. Donor, procedure, and product data were recorded. ADP, collagen, and U46619 (a thromboxane‐A2 analog)‐induced PLT aggregation was investigated in basal (donor) and final (plateletpheresis unit) samples. The expression of PLT activation marker P‐selectin (CD62P) was studied using flow cytometry in basal and final samples. In all cases, P‐selectin was investigated in final samples after stimulation with ADP to assess for a possible further release of the antigen. Four additional plateletpheresis procedures were performed in donors from Group A, using the traditional, nonplasma‐reduced program. RESULTS: Plateletpheresis obtained by means of the Trima device showed a lower response to in‐vitro induced PLT aggregation and a higher percentage of P‐selectin‐expressing PLT when compared to products obtained using the Spectra device. Moreover, P‐selectin release after ADP stimulation was reduced in plateletpheresis units obtained using the Trima device. These differences disappeared when a nonplasma‐reduced collection program was used. In‐vivo evaluation did not detect any difference between platelepheresis obtained by means of the two cell separators. CONCLUSIONS: Plateletpheresis units obtained by means of multicomponent collection show a higher degree of PLT activation compared to traditional plateletpheresis procedures when high‐concentration plasma‐reduced products are collected. Randomized clinical studies are needed to assess the real impact of these findings in terms of in‐vivo efficacy of plasma‐reduced plateletpheresis units.
The killer cell immunoglobulin-like receptor (KIR)-human leukocyte antigen (HLA) interaction represents an example of genetic epistasis, where the concomitant presence of specific genes or alleles encoding receptor-ligand units is necessary for the activity of natural killer (NK) cells. Although KIR and HLA genes segregate independently, they co-evolved under environmental pressures to maintain particular KIR-HLA functional blocks for species survival. We investigated, in 270 Italian healthy individuals, the distribution of KIR and HLA polymorphisms in three climatic areas (from cold north to warm south), to verify their possible geographical stratification. We analyzed the presence of 13 KIR genes and genotyped KIR ligands belonging to HLA class I: HLA-C, HLA-B and HLA-A. We did not observe any genetic stratification for KIR genes and HLA-C ligands in Italy. By contrast, in a north-to-south direction, we found a decreasing trend for the HLA-A3 and HLA-A11 ligands (P = 0.012) and an increasing trend for the HLA-B ligands carrying the Bw4 epitope (P = 0.0003) and the Bw4 Ile80 epitope (P = 0.0005). The HLA-A and HLA-B KIR ligands were in negative linkage disequilibrium (correlation coefficient -0.1211), possibly as a consequence of their similar function in inhibiting NK cells. The distribution of the KIR-HLA functional blocks was different along Italy, as we observed a north-to-south ascending trend for KIR3DL1, when coupled with HLA-B Bw4 ligands (P = 0.0067) and with HLA-B Bw4 Ile80 (P = 0.0027), and a descending trend for KIR3DL2 when coupled with HLA-A3 and HLA-A11 ligands (P = 0.0044). Overall, people from South Italy preferentially use the KIR3DL1-HLA-B Bw4 functional unit, while those from the North Italy equally use both the KIR3DL2-HLA-A3/A11 and the KIR3DL1-HLA-B Bw4 functional units to fight infections. Thus, only KIR3DL receptors, which exert the unique role of microbial sensors through the specific D0 domain, and their cognate HLA-A and HLA-B ligands are selectively pressured in Italy according to geographical north-to-south distribution.
The Spectra LRS Turbo version 7.0 release showed a better CE and resulted in a higher platelet harvest than did the LRS version 5.1. High predonation platelet counts allow a higher platelet yield.
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